In an example, a biomarker includes a specific physical trait used to measure effects of or progress of a disease. For example, concentration of a protein in blood may be a biomarker, when the concentration exceeds a threshold level. In this example, the concentration of the protein reflects the severity or the presence of a disease, including, e.g., cancer.
In another example, biomarkers include substances used as indicators of a biological state. In this example, biomarkers can be used to identify healthy or non-healthy cells/tissues, including, e.g., cancerous cells.